Adjustment of power and frequency based on three or more states

ABSTRACT

Systems and methods for adjusting power and frequency based on three or more states are described. One of the methods includes receiving a pulsed signal having multiple states. The pulsed signal is received by multiple radio frequency (RF) generators. When the pulsed signal having a first state is received, an RF signal having a pre-set power level is generated by a first RF generator and an RF signal having a pre-set power level is generated by a second RF generator. Moreover, when the pulsed signal having a second state is received, RF signals having pre-set power levels are generated by the first and second RF generators. Furthermore, when the pulsed signal having a third state is received, RF signals having pre-set power levels are generated by the first and second RF generators.

CLAIM OF PRIORITY

This application is a continuation of and claims the benefit of andpriority, under 35 U.S.C. § 120, to U.S. patent application Ser. No.15/219,918, filed on Jul. 26, 2016, and titled “Adjustment of Power andFrequency Based on Three or More States”, which is a divisional of andclaims the benefit of and priority, under 35 U.S.C. § 120, to U.S.patent application Ser. No. 14/016,841, filed on Sep. 3, 2013, titled“Adjustment of Power and Frequency Based on Three or More States”, andissued as U.S. Pat. No. 9,462,672, which claims the benefit of andpriority to, under 35 U.S.C. § 119(e), to U.S. Provisional PatentApplication No. 61/701,574, filed on Sep. 14, 2012, and titled“Sub-state Based Adjustment of Power and Frequency”, all of which arehereby incorporated by reference in their entirety for all purposes.

The U.S. patent application Ser. No. 14/016,841 is acontinuation-in-part of and claims the benefit of and priority, under 35U.S.C. § 120, to U.S. patent application Ser. No. 13/620,386, filed onSep. 14, 2012, titled “State-based Adjustment of Power and Frequency”,and issued as U.S. Pat. No. 9,197,196, which claims the benefit of andpriority, under 35 U.S.C. § 119(e), to U.S. Provisional PatentApplication No. 61/602,040, filed on Feb. 22, 2012, and titled“Frequency Enhanced Impedance Dependent Power Control ForMulti-frequency Pulsing”, all of which are incorporated by referenceherein in their entirety for all purposes.

The U.S. patent application Ser. No. 13/620,386 is acontinuation-in-part of and claims the benefit of and priority, under 35U.S.C. § 120, to U.S. patent application Ser. No. 13/531,491, filed onJun. 22, 2012, issued as U.S. Pat. No. 9,114,666, and titled “Methodsand Apparatus For Controlling Plasma In A Plasma Processing System”,which is incorporated by reference herein in its entirety.

The U.S. patent application Ser. No. 14/016,841 is acontinuation-in-part of and claims the benefit of and priority, under 35U.S.C. § 120, to U.S. patent application Ser. No. 13/666,912, filed onNov. 1, 2012, titled “Impedance-based Adjustment of Power andFrequency”, which claims the benefit of and priority, under 35 U.S.C. §119(e), to U.S. Provisional Patent Application No. 61/701,560, filed onSep. 14, 2012, and titled “Impedance-based Adjustment of Power andFrequency”, all of which are incorporated by reference herein in theirentirety for all purposes.

The U.S. patent application Ser. No. 13/666,912 is acontinuation-in-part of and claims the benefit of and priority, under 35U.S.C. § 120, to U.S. patent application Ser. No. 13/531,491, issued asU.S. Pat. No. 9,114,666, filed on Jun. 22, 2012, and titled “Methods andApparatus For Controlling Plasma In A Plasma Processing System”, whichis incorporated by reference herein in its entirety for all purposes.

The U.S. patent application Ser. No. 13/531,491 claims the benefit ofand priority, under 35 U.S.C. § 119(e), to U.S. Provisional PatentApplication No. 61/602,040, filed on Feb. 22, 2012, and titled“Frequency Enhanced Impedance Dependent Power Control ForMulti-frequency Pulsing”, which is incorporated by reference herein inits entirety for all purposes.

The U.S. patent application Ser. No. 13/531,491 claims the benefit ofand priority, under 35 U.S.C. § 119(e), to U.S. Provisional PatentApplication No. 61/602,041, and filed on Feb. 22, 2012, which isincorporated by reference herein in its entirety for all purposes.

The U.S. patent application Ser. No. 13/666,912 is acontinuation-in-part of and claims the benefit of and priority, under 35U.S.C. § 120, to U.S. patent application Ser. No. 13/550,719, filed onJul. 17, 2012, titled “Methods and Apparatus For Synchronizing RF PulsesIn A Plasma Processing System”, and issued as U.S. Pat. No. 9,368,329,which is incorporated by reference herein in its entirety for allpurposes.

The U.S. patent application Ser. No. 13/550,719 claims the benefit ofand priority, under 35 U.S.C. § 119(e), to U.S. Provisional PatentApplication No. 61/602,041, filed on Feb. 22, 2012, and titled“Frequency Enhanced Impedance Dependent Power Control ForMulti-frequency Pulsing”, which is incorporated by reference herein inits entirety for all purposes.

FIELD

The present embodiments relate to improving response time to a change inplasma impedance, and more particularly, apparatus, methods, andcomputer programs for adjustment of power and frequency based on threeor more states.

BACKGROUND

In some plasma processing systems, multiple radio frequency (RF) signalsare provided to one or more electrodes within a plasma chamber. The RFsignals help generate plasma within the plasma chamber. The plasma isused for a variety of operations, e.g., clean substrate placed on alower electrode, etch the substrate, etc.

It is in this context that embodiments described in the presentdisclosure arise.

SUMMARY

Embodiments of the disclosure provide apparatus, methods and computerprograms for adjustment of power and frequency based on three or morestates. It should be appreciated that the present embodiments can beimplemented in numerous ways, e.g., a process, an apparatus, a system, adevice, or a method on a computer readable medium. Several embodimentsare described below.

In some embodiments, a plasma processing system is described. The plasmasystem includes a primary generator including three primary powercontrollers. Each of the primary power controllers is configured with apredefined power setting. The plasma system includes a secondarygenerator including three secondary power controllers. Each of thesecondary power controllers is configured with a predefined powersetting. The plasma system includes a control circuit interfaced as aninput to each of the primary and secondary generators. The controlcircuit is configured to generate a pulsed signal, which is defined toinclude three states that define a cycle that repeats during operationfor a plurality of cycles. Each state is defined to select a first, or asecond or a third of the three primary power controllers while alsoselecting a first, or a second or a third of the three secondary powercontrollers.

In an embodiment, a plasma system that is configured to operate based onmultiple states is described. The plasma system includes a primary radiofrequency (RF) generator for receiving a pulsed signal. The pulsedsignal has three or more states. The three or more states include afirst state, a second state, and a third state. The primary RF generatoris configured to couple to a plasma chamber via an impedance matchingcircuit. The plasma system further includes a secondary RF generator forreceiving the pulsed signal. The secondary RF generator is configured tocouple to the plasma chamber via the impedance matching circuit. Each ofthe primary RF generator and the secondary RF generator is configured todetermine whether the pulsed signal is in the first state, or the secondstate, or the third state. The primary RF generator is configured toprovide an RF signal having a first primary quantitative level to theimpedance matching circuit in response to determining that the pulsedsignal is in the first state. The secondary RF generator is configuredto provide an RF signal having a first secondary quantitative level tothe impedance matching circuit in response to determining that thepulsed signal is in the first state. The primary RF generator isconfigured to provide an RF signal having the first primary quantitativelevel to the impedance matching circuit in response to determining thatthe pulsed signal is in the second state. The secondary RF generator isconfigured to provide an RF signal having a second secondaryquantitative level to the impedance matching circuit in response todetermining that the pulsed signal is in the second state. The primaryRF generator is configured to provide an RF signal having a secondprimary quantitative level to the impedance matching circuit in responseto determining that the pulsed signal is in the third state. Thesecondary RF generator is configured to provide an RF signal having athird secondary quantitative level to the impedance matching circuit inresponse to determining that the pulsed signal is in the third state.

In several embodiments, a plasma system that is configured to operatebased on multiple states is described. The plasma system includes aprimary radio frequency (RF) generator for receiving a pulsed signal,which has three or more states. The three or more states include a firststate, a second state, and a third state. The primary RF generator isconfigured to couple to a plasma chamber via an impedance matchingcircuit. The primary RF generator is configured to determine whether thepulsed signal is in the first state, or the second state, or the thirdstate. The primary RF generator is configured to provide an RF signalhaving a first primary quantitative level to a plasma chamber to strikeplasma in response to determining that the pulsed signal is in the firststate, is configured to provide an RF signal having the first primaryquantitative level to the plasma chamber in response to determining thatthe pulsed signal is in the second state, and is configured to providean RF signal having a second primary quantitative level to the plasmachamber in response to determining that the pulsed signal is in thethird state. The plasma system includes a secondary RF generator that isconfigured to couple to the plasma chamber via the impedance matchingcircuit. The secondary RF generator determines whether a parameterassociated with the plasma exceeds a first threshold. The secondary RFgenerator is configured to provide an RF signal having a first secondaryquantitative level in response to determining that the parameterassociated with the plasma does not exceed the first threshold and isconfigured to provide an RF signal having a second secondaryquantitative level in response to determining that the parameterassociated with the plasma exceeds the first threshold.

In some embodiments, a plasma method includes receiving a pulsed signal.The operation of receiving the pulsed signal is performed by a primaryprocessor. The plasma method further includes receiving the pulsedsignal. The operation of receiving the pulsed signal is performed by asecondary processor. The method includes determining whether the pulsedsignal is in the first state, or the second state, or the third state.The operation of determining whether the pulsed signal is in the firststate, or the second state, or the third state is performed by theprimary processor. The method includes determining whether the pulsedsignal is in the first state, or the second state, or the third state.The operations of determining whether the pulsed signal is in the firststate, or the second state, or the third state is performed by thesecondary processor. The method further includes providing a firstprimary quantitative level of a first radio frequency (RF) signal to aprimary power supply in response to determining that the pulsed signalis in the first state. The operation of providing the first primaryquantitative level is performed by the primary processor. The methodincludes providing a first secondary quantitative level of a second RFsignal to a secondary power supply in response to determining that thepulsed signal is in the first state. The operation of providing thefirst secondary quantitative level is performed by the secondaryprocessor.

In these embodiments, the plasma method includes providing the firstprimary quantitative level of the first RF signal to the primary powersupply in response to determining that the pulsed signal is in thesecond state. The operation of providing the first primary quantitativelevel is performed by the primary processor. The method includesproviding a second secondary quantitative level of the second RF signalto the secondary power supply in response to determining that the pulsedsignal is in the second state. The operation of providing the secondsecondary quantitative level is performed by the secondary processor.The method includes providing a second primary quantitative level of thefirst RF signal to the primary power supply in response to determiningthat the pulsed signal is in the third state. The operation of providingthe second primary quantitative level is performed by the primaryprocessor. The method includes providing a third secondary quantitativelevel of the second RF signal to the secondary power supply in responseto determining that the pulsed signal is in the third state. Theoperation of providing the third secondary quantitative level isperformed by the secondary processor.

Some advantages of the above-described embodiments include reducing aresponse time to respond to a change in plasma impedance within a plasmachamber. For example, when a pulsed signal, e.g., atransistor-transistor logic (TTL) signal, etc., is used to controlfrequency and/or power supplied by multiple RF power supplies, a firstone of the RF supplies does not need time to respond to change in powerand/or frequency of a second one of the RF supplies. Usually, when thefrequency and/or power input to the first RF supply is changed, there isa change in plasma impedance and the first RF supply reacts to thechange in the impedance. This reaction takes time, which negativelyaffects a process, e.g., etching, deposition, cleaning, etc., occurringwithin the plasma chamber. When the RF supplies react to a change in thestate of the state signal with pre-determined frequencies and/orpre-determined power, the time to react to the change in plasmaimpedance is reduced. This reduction in time results in a reduction intime that used to negatively affect the process.

Some additional advantages of the above-described embodiments includeproviding an accurate power and/or frequency level to stabilize plasma,e.g., to reduce a difference between an impedance of a source and aload. The frequency and/or power level is accurate when the power and/orfrequency level is generated based on a change in plasma impedance. Forexample, complex voltage and complex current are measured and are usedto generate a change in plasma impedance. It is determined whether thechange in plasma impedance exceeds a threshold and if so, the powerand/or frequency level is changed to stabilize plasma.

Other advantages of embodiments include reducing an amount of time toachieve stability in plasma. A training routine is used to determinefrequency and/or power levels to apply to a driver and amplifier system.The power and/or frequency levels correspond to a change in plasmaimpedance that is also determined during the training routine. Thetraining routine saves time during production, e.g., time for cleaningsubstrates, time for processing substrates, time for etching substrates,time for deposition material on substrates, etc. For example, duringproduction, when it is determined that the change in plasma impedanceexceeds a threshold, the power and/or frequency levels are applied to apower supply without a need to tune the power and/or frequency levels.

Other aspects will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram of a system for adjusting power and/orfrequency of a radio frequency (RF) generator based on multiple statesof a pulsed signal, in accordance with an embodiment described in thepresent disclosure.

FIG. 2 is a graph that illustrates states S1, S2, and S3, in accordancewith an embodiment described in the present disclosure.

FIG. 3 is a diagram of a graph that illustrates different time periodsfor different states, in accordance with an embodiment described in thepresent disclosure.

FIG. 4 is a diagram of a system for selecting one of auto frequencytuners (AFTs) based on a state of the pulsed signal, in accordance withan embodiment described in the present disclosure.

FIG. 5 is a diagram of a system for controlling a frequency and/or powerof an RF signal that is generated by a y MHz RF generator based on astate of the pulsed signal and a change in impedance of plasma, inaccordance with an embodiment described in the present disclosure.

FIG. 6 is a diagram of a table illustrating a comparison of a change inimpedance with a threshold to determine a power level or a frequencylevel of an RF signal supplied by an RF generator, in accordance with anembodiment described in the present disclosure.

FIG. 7 is a diagram of a system for selecting an AFT based on a state ofthe pulsed signal and based on whether a parametric value exceeds athreshold, in accordance with an embodiment described in the presentdisclosure.

FIG. 8A is a diagram of graphs to illustrate signals generated by two RFgenerators, where one of the signals has a different power value foreach state and another one of the signals has a power value of zeroduring a state, in accordance with an embodiment described in thepresent disclosure.

FIG. 8B is a diagram of graphs to illustrate signals generated by two RFgenerators, where one of the signals has a same power value for twostates and another one of the signals has a power value of zero during astate, in accordance with an embodiment described in the presentdisclosure.

FIG. 9A is a diagram of graphs to illustrate signals generated by two RFgenerators, where one of the signals has a different power value foreach state and another one of the signals has a non-zero power valueduring all states, in accordance with an embodiment described in thepresent disclosure.

FIG. 9B is a diagram of graphs to illustrate signals generated by two RFgenerators, where one of the signals has a same power value for twostates and another one of the signals has a non-zero power value duringall states, in accordance with an embodiment described in the presentdisclosure.

FIG. 10A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has a power value of zero duringa state, and yet another one of the signals has a constant power valueduring all states, in accordance with an embodiment described in thepresent disclosure.

FIG. 10B is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a same power value for twostates and another one of the signals has a power value of zero during astate, and yet another one of the signals has a constant power valueduring all states, in accordance with an embodiment described in thepresent disclosure.

FIG. 11A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has a non-zero power value duringall states, and yet another one of the signals has a constant powervalue during all states, in accordance with an embodiment described inthe present disclosure.

FIG. 11B is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a same power value for twostates and another one of the signals has a non-zero power value duringall states, and yet another one of the signals has a constant powervalue during all states, in accordance with an embodiment described inthe present disclosure.

FIG. 12A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has a power value of zero duringa state, and yet another one of the signals has a same power value fortwo states, in accordance with an embodiment described in the presentdisclosure.

FIG. 12B is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has the same power value for twostates, another one of the signals has a power value of zero during astate, and yet another one of the signals has a same power value for twostates, in accordance with an embodiment described in the presentdisclosure.

FIG. 13A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has non-zero power values for allstates, and yet another one of the signals has a same power value fortwo states, in accordance with an embodiment described in the presentdisclosure.

FIG. 13B is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has the same power value for twostates, another one of the signals has non-zero power values for allstates, and yet another one of the signals has a same power value fortwo states, in accordance with an embodiment described in the presentdisclosure.

FIG. 14A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has a power value of zero duringa state, and yet another one of the signals has a same power value fortwo states, in accordance with an embodiment described in the presentdisclosure.

FIG. 14B is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has the same power value for twostates, another one of the signals has a power value of zero during astate, and yet another one of the signals has a same power value for twostates, in accordance with an embodiment described in the presentdisclosure.

FIG. 15A is a diagram of graphs to illustrate signals generated by threeRF generators, where one of the signals has a different power value foreach state, another one of the signals has non-zero power values for allstates, and yet another one of the signals has a same power value fortwo states, in accordance with an embodiment described in the presentdisclosure.

FIG. 15B is a diagram of embodiments of graphs to illustrate signalsgenerated by three RF generators, where one of the signals has the samepower value for two states, another one of the signals has non-zeropower values for all states, and yet another one of the signals has asame power value for two states, in accordance with an embodimentdescribed in the present disclosure.

DETAILED DESCRIPTION

The following embodiments describe systems and methods for adjustment ofpower and frequency based on three or more states. It will be apparentthat the present embodiments may be practiced without some or all ofthese specific details. In other instances, well known processoperations have not been described in detail in order not tounnecessarily obscure the present embodiments.

FIG. 1 is a block diagram of an embodiment of a system 100 foradjusting, during production, power and/or frequency of an RF generatorbased on multiple states of a pulsed signal 102. The system 100 includesan x megahertz (MHz) radio frequency (RF) power generator that generatesan RF signal and the RF signal is supplied via an impedance matchingcircuit 106 to a lower electrode 120 of a plasma chamber 104. Similarly,a y MHz power supply generates an RF signal and supplies the RF signalvia the impedance matching circuit 106 to the lower electrode 120.

Values of x may be 2, 27, or 60. Also, values of y may be 27, 60, or 2.For example, when x is 2, y is 27 or 60. As another example, when x is27, y is 2 or 60. As yet another example, when x is 60, y is 2 or 27.Moreover, it should be noted that the values 2 MHz, 27 MHz, and 60 MHzare provided as examples and are not limiting. For example, instead of a2 MHz RF generator, a 2.5 MHz RF generator may be used and instead of a60 MHz RF generator, a 65 MHz RF generator may be used. In oneembodiment, in addition to the 2 MHz RF generator and the 27 MHz RFgenerator, the 60 MHz RF generator is used to provide RF power to thelower electrode 120.

An impedance matching circuit includes electric circuit components,e.g., inductors, capacitors, etc. to match an impedance of a sourcecoupled to the impedance matching circuit with an impedance of a loadcoupled to the impedance matching circuit. For example, the impedancematching circuit 106 matches an impedance of the x MHz RF generator andany components, e.g., an RF cable, etc., coupling the x MHz RF generatorto the impedance matching circuit 106 with an impedance of the plasmachamber 104 and any components, e.g., an RF transmission line, etc.,coupling the plasma chamber 104 to the impedance matching circuit 106.In one embodiment, an impedance matching circuit is tuned to facilitatea match between an impedance of a source coupled to the impedancematching circuit with that of a load coupled to the impedance matchingcircuit. An impedance match between a source and a load reduces chancesof power being reflected from the load towards the source.

The plasma chamber 104 includes the lower electrode 120, an upperelectrode 122, and other components (not shown), e.g., an upperdielectric ring surrounding the upper electrode 122, a lower electrodeextension surrounding the upper dielectric ring, a lower dielectric ringsurrounding the lower electrode, a lower dielectric ring surrounding thelower electrode 120, a lower electrode extension surrounding the lowerelectrode 120, an upper plasma exclusion zone (PEZ) ring, a lower PEZring, etc. The upper electrode 122 is located opposite to and facing thelower electrode 120.

A substrate 124, e.g., a semiconductor wafer, is supported on an uppersurface 126 of the lower electrode 120. Integrated circuits, e.g., anapplication specific integrated circuit (ASIC), a programmable logicdevice (PLD), etc., are developed on the substrate 124 and theintegrated circuits are used in a variety of devices, e.g., cell phones,tablets, smart phones, computers, laptops, networking equipment, etc.The lower electrode 120 is made of a metal, e.g., anodized aluminum,alloy of aluminum, etc. Also, the upper electrode 122 is made of ametal, e.g., aluminum, alloy of aluminum, etc.

In one embodiment, the upper electrode 122 includes a hole that iscoupled to a central gas feed (not shown). The central gas feed receivesone or more process gases from a gas supply (not shown). Examples of aprocess gases include an oxygen-containing gas, such as O₂. Otherexamples of a process gas include a fluorine-containing gas, e.g.,tetrafluoromethane (CF₄), sulfur hexafluoride (SF₆), hexafluoroethane(C₂F₆), etc. The upper electrode 122 is grounded. The lower electrode120 is coupled to one or more RF generators via the impedance matchingcircuit 106. For example, the upper electrode 122 is coupled to the xMHz RF generator via the impedance matching circuit 106 and to the y MHzRF power supply via the impedance matching circuit 106.

When the process gas is supplied between the upper electrode 122 and thelower electrode 120 and when an RF generator, e.g., the x MHz RFgenerator and/or the y MHz RF generator, etc., supplies power via theimpedance matching circuit 106 to the lower electrode 120, the processgas is ignited to generate plasma within the plasma chamber 104. Forexample, the 2 MHz RF generator supplies power via the impedancematching circuit 106 to ignite the process gas to generate plasma. Insome embodiments, the 2 MHz RF generator is a master RF generator.

A tool user interface (UI) 151, e.g., a control circuit, etc., on acomputer (not shown) is used to generate the pulsed signal 102, e.g., atransistor-transistor logic (TTL) signal, a digital pulsing signal, aclock signal, a signal with a duty cycle, etc. In one embodiment, thecomputer includes a TTL circuit. As used herein, instead of a computer,a processor, a controller, an ASIC or a PLD is used, and these terms areused interchangeably herein.

The pulsed signal 102 includes states S1, S2, and S3. In variousembodiments, the states S1, S2, and S3 repeat in clock cycles. Eachclock cycle includes the state S1, S2 and S3. For example, during a halfperiod of a clock cycle, the states S1 and S2 are executed and duringthe remaining half period of the clock cycle, the state S3 is executed.As another example, during a third of a time period of a clock cycle,the state S1 is executed, during another third of the time period, thestate S2 is executed, and during the remaining third of the time period,the state S3 is executed. In some embodiments, the pulsed signal 102includes more or less than three states. An example of the state S1includes a state having a first range of power levels. An example of thestate S2 includes a state having a second range of power levels. Asexample of the third state S3 includes a state having a third range ofpower levels. In some embodiments, the second range of power levels isgreater than the first range of power levels and the third range ofpower levels is greater than the second range of power levels. Invarious embodiments, the third range of power levels is lower than thesecond range of power levels and the second range of power levels islower than the first range of power levels. In one embodiment, the thirdrange of power levels is unequal to the second range of power levels andthe second range of power levels is unequal to the first range of powerlevels.

In some embodiments, a range of power levels includes one or more powerlevels.

In various embodiments, instead of the computer, a clock source, e.g., acrystal oscillator, etc., is used to generate an analog clock signal,which is converted by an analog-to-digital converter into a digitalsignal similar to the pulsed signal 102. For example, a crystaloscillator is made to oscillate in an electric field by applying avoltage to an electrode near or on the crystal oscillator.

In some embodiments, two digital clock sources, e.g., processors,computers, etc., are used to generate the pulsed signal 102. A firstclock signal of the first digital clock source has a state 1 and 0 and asecond clock signal of the second digital clock source has a state 1 and0. An adder, e.g., an addition circuit, etc., is coupled with the twoclock sources to sum the first and second digital signals to generatethe pulsed signal 102 with three states.

The pulsed signal 102 is sent to a digital signal processor (DSP) 140 ofthe x MHz RF generator and another DSP 153 of the y MHz RF generator.Each DSP 140 and 153 receives the pulsed signal 102 and identifies thestates S1, S2, and S3 of the pulsed signal 102. For example, the DSP 140distinguishes between the states S1, S2, and S3. To illustrate a mannerin which the DSP 140 distinguishes between the states S1, S2, and S3,the DSP 140 determines that the pulsed signal 102 has the first range ofpower levels during a first time period, has the second range of powerlevels during a second time period, and has the third range of powerlevels during a third time period. It is pre-determined by the DSP 140that the first range of power levels corresponds to the state S1, thesecond range of power levels corresponds to the state S2, and the thirdrange of power levels corresponds to the state S3.

In some embodiments, the first time period is equal to each of thesecond time period and to the third time period. In various embodiments,the first time period is equal to the first time period or to the secondtime period. In one embodiment, the first time period is unequal to eachof the first and second time periods. In various embodiments, the firsttime period is unequal to the first time period or the second timeperiod.

Each DSP 140 and 153 stores the states S1, S2, and S3 in memorylocations of one or more memory devices within the DSP. Examples of amemory device include a random access memory (RAM) and a read-onlymemory (ROM). A memory device may be a flash memory, a hard disk, astorage device, a computer-readable medium, etc.

In various embodiments, a correspondence between a range of power levelsand a state of the pulsed signal 102 is stored in a memory device of aDSP. For example, a mapping between the first range of power levels andthe state S1 is stored within a memory device of the DSP 140. As anotherexample, a mapping between the second range of power levels and thestate S2 is stored within a memory device of the DSP 153. As yet anotherexample, a mapping between the third range of power levels and the stateS3 is stored within the DSP 140.

Each DSP 140 and 153 provides the identified states S1, S2, and S3 fromcorresponding memory locations to corresponding auto frequency tuners(AFTs) 130, 132, 134, 138, 141, and 142, and to corresponding powercontrollers 144, 146, 148, 150, 152, and 154. For example, the DSP 140indicates to the AFT 130 and the power controller 144 that the pulsedsignal 102 is in the state S1 between times t1 and t2 of the first timeperiod. As another example, the DSP 140 indicates to the AFT 132 and thepower controller 146 that the pulsed signal 102 is in the state S2between times t2 and t3 of the second time period. As yet anotherexample, the DSP 140 indicates to the AFT 134 and the power controller148 that the pulsed signal 102 is in the state S3 between times t3 andt4 of the third time period. As another example, the DSP 153 indicatesto the AFT 138 and the power controller 150 that the pulsed signal 102is in the state S1 between the times t1 and t2 of the first time period.As yet another example, the DSP 153 indicates to the AFT 141 and thepower controller 152 that the pulsed signal 102 is in the state S2between the times t2 and t3 of the second time period. As anotherexample, the DSP 153 indicates to the AFT 142 and the power controller154 that the pulsed signal 102 is in the state S3 between the times t3and t4 of the third time period. In some embodiments, the terms tunerand controller are used interchangeably herein. An example of an AFT isprovided in U.S. Pat. No. 6,020,794, which is incorporated by referenceherein in its entirety.

Each AFT 130, 132, 134, 138, 141, and 142 determines a frequency levelbased on a state of the pulsed signal 102 and each power controller 144,146, 148, 150, 152, and 154 determines a power level based on the stateof the pulsed signal 102. For example, the AFT 130 determines that afrequency level Fp1 is to be provided to a power supply 160 of the x MHzRF generator when the state of the pulsed signal 102 is S1 and the powercontroller 144 determines that a power level Pp1 is to be provided tothe power supply 160 when the state of the pulsed signal 102 is S1. Asanother example, the AFT 132 determines that a frequency level Fp2 is tobe provided to the power supply 160 when the state of the pulsed signal102 is S2 and the power controller 146 determines that a power level Pp2is to be provided to the power supply 160 when the state of the pulsedsignal 102 is S2. As yet another example, the AFT 134 determines thatthe frequency level Fp3 is to be provided to the power supply 160 whenthe state of the pulsed signal 102 is S3 and the power controller 148determines that the power level Pp3 is to be provided to the powersupply 160 when the state of the pulsed signal 102 is S3.

As another example, the AFT 138 determines that a frequency level Fs1 isto be provided to a power supply 162 of the y MHz RF generator when thestate of the pulsed signal 102 is S1 and the power controller 150determines that a power level Psi is to be provided to the power supply162 when the state of the pulsed signal 102 is S1. As another example,the AFT 141 determines that a frequency level Fs2 is to be provided tothe power supply 162 when the state of the pulsed signal 102 is S2 andthe power controller 152 determines that a power level Ps2 is to beprovided to the power supply 162 when the state of the pulsed signal 102is S2. As yet another example, the AFT 142 determines that a frequencylevel Fs3 is to be provided to the power supply 162 when the state ofthe pulsed signal 102 is S3 and the power controller 154 determines thata power level Ps3 is to be provided to the power supply 162 when thestate of the pulsed signal 102 is S3.

In several embodiments, a level includes one or more values. Forexample, a frequency level includes one or more frequency values and apower level includes one or more power values.

In some embodiments, the frequency levels Fp1, Fp2, and Fp3 are thesame. In various embodiments, at least two of the frequency levels Fp1,Fp2, and Fp3 are unequal. For example, the frequency level Fp1 isunequal to the frequency level Fp2, which is unequal to the frequencylevel Fp3. In this example, the frequency level Fp3 is unequal to thefrequency level Fp1. As another example, the frequency level Fp1 isunequal to the frequency level Fp2, which is equal to the frequencylevel Fp3.

Similarly, in several embodiments, the frequency levels Fs1, Fs2, andFs3 are the same, or at least two of the frequency levels Fs1, Fs2, andFs3 are unequal and the remaining frequency levels are equal, or atleast two of the frequency levels Fsl, Fs2, and Fs3 are equal and theremaining frequency levels are unequal.

In various embodiments, the power levels Pp1, Pp2, and Pp3 are the same.For example, the power level Ppl is equal to the power level Pp2, whichis equal to the power level Pp3. In a number of embodiments, at leasttwo of the power levels Ppl, Pp2, and Pp3 are unequal and the remainingpower levels are equal. For example, the power level Ppl is unequal tothe power level Pp2, which is equal to the power level Pp3. As yetanother example, the power level Pp2 is unequal to the power level Pp3,which is equal to the power level Ppl. As another example, the powerlevel Ppl is equal to the power level Pp2, which is unequal to the powerlevel Pp3. In some embodiments, at least two of the power levels Pp1,Pp2, and Pp3 are equal and the remaining power levels are unequal.

Similarly, in some embodiments, the power levels Psi, Ps2, and Ps3 arethe same. In various embodiments, at least two of the power levels Psi,Ps2, and Ps3 are unequal and the remaining power levels are equal. Inseveral embodiments, at least two of the power levels Ps1, Ps2, and Ps3are equal and the remaining power levels are unequal.

In one embodiment, the frequency level Fsl and the power level Ps1 aregenerated based on a training routine. During the training routine, whenthe x MHz RF generator changes its RF power signal from a low powerlevel to a high power level or from the low power level to the highpower level, there is an impedance mismatch between one or more portionswithin the plasma chamber 104 and y MHz RF generator. The high powerlevel is higher than the low power level. The x MHz RF generator changesits RF power signal when a state of the pulsed signal 102 supplied tothe x MHz RF generator changes from S3 to S1. In this case, the y MHz RFgenerator has its frequency and power tuned when the x MHz RF generatorstarts supplying power at the high power level or at the low powerlevel. To reduce the impedance mismatch, the y MHz RF generator startstuning, e.g., converging, to a frequency level and to a power level. Theachievement of convergence may be determined by the DSP 153 based on astandard deviation or another technique. To allow the y MHz RF generatormore time to converge to the frequency level and the power level, the xMHz RF generator is kept at the high power level or the low power levelfor an extended period of time than a usual period of time. The usualperiod of time is an amount of time in which the impedance mismatch isnot reduced, e.g., removed. When the y MHz RF generator converges to thefrequency level and the power level, the converged frequency level isstored as the frequency level Fsl within the AFT 138 and the convergedpower level is stored as the power level Psi within the power controller150. Similarly, during the training routine, the frequency levels Fs2,Fs3, Fp1, Fp2, and Fp3, and the power levels Ps2, Ps3, Pp1, Pp2, and Pp3are generated. The frequency level Fs2 is stored in the AFT 141, thefrequency level Fs3 is stored in the AFT 142, the frequency level Fp1 isstored in the AFT 130, the frequency level Fp2 is stored in the AFT 132,the frequency level Fp3 is stored in the AFT 134, the power level Ps2 isstored in the power controller 152, and the power level Ps3 is stored inthe power controller 154, the power level Ppl is stored in the powercontroller 144, and the power level Pp2 is stored in the powercontroller 146, and the power level Pp3 is stored in the powercontroller 148.

When the state of the pulsed signal 102 is S1, the power controller 144provides the power level Ppl to the power supply 160 and the powercontroller 150 provides the power level Psi to the power supply 162.During the state S1, the AFT 130 provides the frequency level Fp1 to thepower supply 160 and the AFT 138 provides the frequency level Fsl to thepower supply 162.

Moreover, in one embodiment, when the state of the pulsed signal 102 isS1, the power controller 146 does not supply the power level Pp2 to thepower supply 160 and the power controller 148 does not supply the powerlevel Pp3 to the power supply 160. Also, in this embodiment, the AFT 132does not provide the frequency level of Fp2 to the power supply 160 andthe AFT 134 does not provide the frequency level of Fp3 to the powersupply 160. Also, when the state of the pulsed signal 102 is S1, thepower controller 152 does not supply the power level Ps2 to the powersupply 162 and the power controller 154 does not supply the power levelPs3 to the power supply 162. Furthermore, the AFT 141 does not providethe frequency level of Fs2 to the power supply 162 and the AFT 142 doesnot provide the frequency level of Fs3 to the power supply 162. Invarious embodiments, a non-supply of power level includes a supply of apower level of zero.

In some embodiments, during a state, a power level for the state isprovided to the power supply 160 simultaneous with the provision of apower level for the state to the power supply 162. For example, duringthe state S1, the power level Pp1 is provided to the power supply 160simultaneous with the provision of the power level Ps1 to the powersupply 162. To further illustrate, in the state S1, the power level Pplis provided to the power supply 160 during the same clock edge of thepulsed signal 102 as that during which the power level Psi is providedto the power supply 162.

Similarly, in various embodiments, during a state, a frequency level forthe state is provided to the power supply 160 simultaneous with theprovision of a frequency level for the state to the power supply 162.For example, during the state S1, the frequency level Fp1 is provided tothe power supply 160 simultaneous with the provision of the frequencylevel Fs1 to the power supply 162. To further illustrate, in the stateS1, the frequency level Fp1 is provided to the power supply 160 duringthe same clock edge of the pulsed signal 102 as that during which thefrequency level Fs1 is provided to the power supply 162.

In some embodiments, during a state, a power level for the state and afrequency level for the state is provided to the power supply 160simultaneous with the provision of a power level for the state and afrequency level for the state to the power supply 162. For example,during the state S3, the frequency level Fp3 and the power level Pp3 areprovided simultaneously to the power supply 160 simultaneous with theprovision of the frequency level Fs3 and the power level Ps3 to thepower supply 162. To further illustrate, in the state S1, the frequencylevel Fp3 and the power level Pp3 are provided to the power supply 160during the same clock edge of the pulsed signal 102 as that during whichthe frequency level Fs3 and the power level Ps3 are provided to thepower supply 162.

In several embodiments, during a state, a power level is provided by apower controller of the x MHz RF generator to the power supply 160 ofthe x MHz RF generator at almost the same time as that of the provisionof a power level by a power controller of the y MHz RF generator to thepower supply 162 of the y MHz RF generator. For example, during thestate S1, the power level of Ppl is provided to the power supply 160 atalmost the same time as that of the provision of the power level Ps1 tothe power supply 162. To further illustrate, in the state S1, the powerlevel of Ppl is provided to the power supply 160 within a fraction of asecond, e.g., microseconds, milliseconds, nanoseconds, etc., before orafter an occurrence of a clock edge of the pulsed signal 102. In thisexample, the power level Psi is provided to the power supply 162 duringthe occurrence of the clock edge.

Similarly, in some embodiments, during a state, a frequency level isprovided by an AFT of the x MHz RF generator to the power supply 160 ofthe x MHz RF generator at almost the same time as that of the provisionof a frequency level by an AFT of the y MHz RF generator to the powersupply 162 of the y MHz RF generator. For example, during the state S2,the frequency level of Fp2 is provided to the power supply 160 at almostthe same time as that of the provision of the frequency level Fs2 to thepower supply 162. To further illustrate, in the state S2, the frequencylevel of Fp2 is provided to the power supply 160 within a fraction of asecond before or after an occurrence of a clock edge of the pulsedsignal 102. In this example, the power level Fs2 is provided to thepower supply 162 during the occurrence of the clock edge.

Similarly, in various embodiments, during a state, a frequency level isprovided by a tuner of the x MHz RF generator and a power level isprovided by a power controller of the x MHz RF generator to the powersupply 160 of the x MHz RF generator at almost the same time as afrequency level is provided by a tuner of the y MHz RF generator and apower level is provided by a power controller of the y MHz RF generatorto the power supply 162 of the y MHz RF generator. For example, duringthe state S3, the frequency level of Fp3 and the power level of Pp3 areprovided to the power supply 160 at almost the same time as that of theprovision of the frequency level Fs3 and the power level Ps3 to thepower supply 162. To further illustrate, in the state S3, the frequencylevel Fp3 and the power level Pp3 are provided to the power supply 160within a fraction of a second before or after an occurrence of a clockedge of the pulsed signal 102. In this example, the power level Ps3 andthe frequency level Fs3 are provided to the power supply 162 during theoccurrence of the clock edge.

The power supply 160 receives the frequency level of Fp1 and the powerlevel Pp1 during the state S1. Upon receiving the levels Fp1 and Pp1,the power supply 160 generates RF power at the frequency level Fp1 andthe RF power has the power level of Ppl. Moreover, the power supply 162receives the frequency level Fs1 and the power level Psi during thestate S1. Upon receiving the levels Fs1 and Psi, the power supply 162 ofthe y MHz RF generator generates an RF signal having the frequency levelFs1 and the power level Ps1.

Moreover, in one embodiment, when the state of the pulsed signal 102 isS2, the power controller 144 does not supply the power level Pp1 to thepower supply 160 and the power controller 148 does not supply the powerlevel Pp3 to the power supply 160. Also, in this embodiment, the AFT 130does not provide the frequency level of Fp1 to the power supply 160 andthe AFT 134 does not provide the frequency level of Fp3 to the powersupply 160. Also, when the state of the pulsed signal 102 is S2, thepower controller 150 does not supply the power level Psi to the powersupply 162 and the power controller 154 does not supply the power levelPs3 to the power supply 162. Furthermore, during the state S2 of thepulsed signal 102, the AFT 138 does not provide the frequency level ofFs1 to the power supply 162 and the AFT 142 does not provide thefrequency level of Fs3 to the power supply 162.

Moreover, the power supply 160 receives the frequency level of Fp2 andthe power level Pp2 during the state S2. Upon receiving the levels Fp2and Pp2, the power supply 160 generates RF power at the frequency levelFp2 and the RF power has the power level of Pp2. Moreover, the powersupply 162 receives the frequency level Fs2 and the power level Ps2during the state S2. Upon receiving the levels Fs2 and Ps2, the powersupply 162 of the y MHz RF generator generates an RF signal having thefrequency level Fs2 and the power level Ps2.

Also, in one embodiment, when the state of the pulsed signal 102 is S3,the power controller 144 does not supply the power level Ppl to thepower supply 160 and the power controller 146 does not supply the powerlevel Pp2 to the power supply 160. Also, in this embodiment, the AFT 130does not provide the frequency level of Fp1 to the power supply 160 andthe AFT 132 does not provide the frequency level of Fp2 to the powersupply 160. Also, when the state of the pulsed signal 102 is S3, thepower controller 150 does not supply the power level Psi to the powersupply 162 and the power controller 152 does not supply the power levelPs2 to the power supply 162. Furthermore, the AFT 138 does not providethe frequency level of Fs1 to the power supply 162 and the AFT 141 doesnot provide the frequency level of Fs2 to the power supply 162.

Furthermore, the power supply 160 receives the frequency level of Fp3and the power level Pp3 during the state S3. Upon receiving the levelsFp3 and Pp3, the power supply 160 generates an RF signal having thefrequency level Fp3 and the RF power level Pp3. Moreover, the powersupply 162 receives the frequency level Fs3 and the power level Ps3during the state S3. Upon receiving the levels Fs3 and Ps3, the powersupply 162 of the y MHz RF generator generates an RF signal having thefrequency level Fs3 and the power level Ps3.

In one embodiment, during a state, the non-provision of power levels tothe power supply 160 for the remaining states is performed simultaneouswith the non-provision of power levels for the remaining states to thepower supply 162. For example, in the state S1, there is no provision ofa power level by the power controller 146 to the power supply 160 duringthe same edge of the pulsed signal 102 as that of the non-provision of apower level by the power controller 152 to the power supply 162. Asanother example, in the state S2, there is no provision of power levelsby the power controllers 144 and 148 to the power supply 160 during thesame edge of the pulsed signal 102 as that of the non-provision of powerlevels by the power controllers 150 and 154 to the power supply 162. Asyet another example, in the state S3, there is no provision of powerlevels by the power controllers 144 and 146 to the power supply 160during the same edge of the pulsed signal 102 as that of thenon-provision of power levels by the power controllers 150 and 152 tothe power supply 162.

In some embodiments, during a state, the non-provision of frequencylevels to the power supply 160 for the remaining states is performedsimultaneous with the non-provision of frequency levels for theremaining states to the power supply 162. For example, in the state S1,there is no provision of a frequency level by the AFT 132 to the powersupply 160 during the same edge of the pulsed signal 102 as that of thenon-provision of a frequency level by the AFT 141 to the power supply162. As another example, in the state S2, there is no provision offrequency levels by the AFTs 130 and 134 to the power supply 160 duringthe same edge of the pulsed signal 102 as that of the non-provision offrequency levels by the AFTs 138 and 142 to the power supply 162. As yetanother example, in the state S3, there is no provision of frequencylevels by the AFTs 130 and 132 to the power supply 160 during the sameedge of the pulsed signal 102 as that of the non-provision of frequencylevels by the AFTs 138 and 141 to the power supply 162.

In several embodiments, during a state, the non-provision of frequencyand power levels to the power supply 160 for the remaining states isperformed simultaneous with the non-provision of frequency and powerlevels for the remaining states to the power supply 162. For example, inthe state S1, there is no provision of a frequency level by the AFT 132and no provision of a power level by the power controller 146 to thepower supply 160 during the same edge of the pulsed signal 102 as thatof the non-provision of a frequency level by the AFT 141 and anon-provision of a power level by the power controller 152 to the powersupply 162.

In some embodiments, during a state, the non-provision of power levelsto the power supply 160 for the remaining states is performed at almostthe same time as that of the non-provision of power levels for theremaining states to the power supply 162. In various embodiments, duringa state, the non-provision of frequency levels to the power supply 160for the remaining states is performed at almost the same time as thenon-provision of frequency levels for the remaining states to the powersupply 162. In several embodiments, during a state, the non-provision offrequency and power levels to the power supply 160 for the remainingstates is performed at almost the same time as the non-provision offrequency and power levels for the remaining states to the power supply162.

In some embodiments, a power supply, e.g., an RF power supply, etc.,includes a driver coupled to an amplifier. The driver generates an RFsignal. The amplifier amplifies the RF signal and supplies forward powerof the RF signal via an RF cable, the impedance matching circuit 106 andthe RF transmission line 184 to the plasma chamber 104. For example,during the state S1, the amplifier of the power supply 160 suppliesforward power having a power level that is proportional, e.g., same as,multiple of, etc. of the power level Ppl and having the frequency levelFp1 via the RF cable 180, the impedance matching circuit 106, and an RFtransmission line 184 to the plasma chamber 104. In this example, duringthe state S1, the amplifier of the power supply 162 supplies forwardpower having a power level that is proportional to the power level Psiand having the frequency level Fsl via the RF cable 182, the impedancematching circuit 106, and the RF transmission line 184 to the plasmachamber 104.

As another example, during the state S2, the amplifier of the powersupply 160 supplies forward power having a power level that isproportional, e.g., same as, multiple of, etc. of the power level Pp2and having the frequency level Fp2 via the RF cable 180, the impedancematching circuit 106, and the RF transmission line 184 to the plasmachamber 104. In this example, during the state S2, the amplifier of thepower supply 162 supplies forward power having a power level that isproportional to the power level Ps2 and having the frequency level Fs2via the RF cable 182, the impedance matching circuit 106, and the RFtransmission line 184 to the plasma chamber 104. As yet another example,during the state S3, the amplifier of the power supply 160 suppliesforward power having a power level that is proportional, e.g., same as,multiple of, etc. of the power level Pp3 and having the frequency levelFp3 via the RF cable 180, the impedance matching circuit 106, and the RFtransmission line 184 to the plasma chamber 104. In this example, duringthe state S3, the amplifier of the power supply 162 supplies forwardpower having a power level that is proportional to the power level Ps3and having the frequency level Fs3 via the RF cable 182, the impedancematching circuit 106, and the RF transmission line 184 to the plasmachamber 104.

In one embodiment, during each state S1, S2, and S3, a sensor 210 of thex MHz RF generator senses reflected power, which is RF power reflectedfrom the plasma of the plasma chamber 104, on the RF cable 180.Moreover, during each state S1, S2, and S3, the sensor 210 sensesforward power on the RF cable 180 when the forward power is sent fromthe x MHz RF generator via the RF cable 180 to the plasma chamber 104.Similarly, during each state S1, S2, and S3, a sensor 212 of the y MHzRF generator senses reflected power from the plasma of the plasmachamber 104. The reflected power sensed by the sensor 212 is reflectedon the RF cable 182 from the plasma of the plasma chamber 104. Moreover,during each state S1, S2, and S3, the sensor 212 senses forward power onthe RF cable 182 when the forward power is sent from the y MHz RFgenerator via the RF cable 182 to the plasma chamber 104.

An analog-to-digital converter (ADC) 221 of the x MHz RF generatorconverts the reflected power signals and the forward power signalssensed by the sensor 210 from an analog form to a digital form and anADC 223 of the y MHz RF generator converts the reflected power signalsand the forward power signals sensed by the sensor 212 from an analog toa digital form. During each state S1, S2, and S3, the DSP 140 receives adigital value, e.g., a magnitude, a phase, or a combination thereof,etc., of the reflected power signal and a digital value of the forwardpower signal sensed by the sensor 210 and the DSP 153 receives a digitalvalue of the reflected power signal and a digital value of the forwardpower signal sensed by the sensor 212.

In some embodiments, a digital value of a power signal is a voltage ofthe power signal, a current of the signal, or a combination of thevoltage and current. In various embodiments, a digital value of a signalincludes a magnitude of the signal and a phase of the signal.

The DSP 140 calculates a parametric value, e.g., a ratio of the digitalreflected power signal and the digital forward power signal, or avoltage standing wave ratio (VSWR), or a gamma value, or a change inimpedance, etc., during one or all of the states S1, S2, and S3 from thedigital values of the forward and reflected power signals on the RFcable 180. In some embodiments, a gamma value of 1 indicates a highdegree of mismatch between impedances of a source and a load and a gammavalue of 0 indicates a low degree of mismatch between impedances of asource and a load. Similarly, the DSP 153 calculates a parametric valuefrom digital values of forward and reflected power signals on the RFcable 182. In various embodiments, a VSWR is calculated as being equalto a ratio of RC−1 and RC+1, where RC is a reflection coefficient.

In some embodiments, a sensor of an RF generator is a voltage andcurrent probe that measures a complex current and a complex voltage thatis transferred via an RF cable between the RF generator and theimpedance matching circuit 106. For example, the sensor 210 is a voltageand current probe that measures a complex voltage and a complex currentthat is transferred via the RF cable 180 between the x MHz RF generatorand the impedance matching circuit 106. As another example, the sensor212 is a voltage and current probe that measures a complex voltage and acomplex current that is transferred via the RF cable 182 between the yMHz RF generator and the impedance matching circuit 106. In theseembodiments, a parametric value that is measured by a sensor includes animpedance of plasma or a change in impedance of plasma. The impedance ofplasma is determined by a sensor as a ratio of the complex voltage tothe complex current. The change in impedance is determined as adifference between two impedances of plasma over time. In someembodiments, a parametric value is determined by an AFT, a powercontroller, or a DSP of an RF generator.

A parametric value for a state is sent from a DSP of an RF generator toan AFT, within the RF generator, associated with the state. For example,a parametric value obtained during the state S1 is sent from the DSP 140to the AFT 130 and a parametric value obtained during the state S1 issent from the DSP 153 to the AFT 138. As another example, a parametricvalue obtained during the state S2 is sent from the DSP 140 to the AFT132 and a parametric value obtained during the state S2 is sent from theDSP 153 to the AFT 141. As yet another example, a parametric valueobtained during the state S3 is sent from the DSP 140 to the AFT 134 anda parametric value obtained during the state S3 is sent from the DSP 153to the AFT 142.

During a state, an AFT of an RF generator receives a parametric valuefrom a DSP, during the state, of the RF generator and the AFT determinesa frequency level associated with the received parametric value. Forexample, during the state S1, the AFT 130 determines a frequency levelassociated with a parametric value received from the DSP 140 during thestate S1 and the AFT 138 determines a frequency level based on aparametric value during the state S1 received from the DSP 153. Asanother example, during the state S2, the AFT 132 determines a frequencylevel corresponding to a parametric value received from the DSP 140during the state S2 and the AFT 141 determines a frequency level basedon a parametric value during the state S2 received from the DSP 153. Asyet another example, during the state S3, the AFT 134 determines afrequency level associated with a parametric value received from the DSP140 during the state S3 and the AFT 142 determines a frequency levelbased on a parametric value during the state S3 received from the DSP153.

It should be noted that an association, e.g., correspondence, mapping,link, etc., between a parametric value and a frequency level ispre-determined and stored within an AFT. Similarly, in some embodiments,an association between a parametric value and a power level ispre-determined and stored within a power controller.

Moreover, during a state, an AFT of an RF generator adjusts a frequencylevel based on a frequency level that is generated from a parametricvalue for the state and provides the adjusted frequency level to a powersupply of the RF generator. For example, during the state S1, the AFT130 adjusts the frequency level Fp1 based on a frequency levelassociated with a parametric value generated by the DSP 140 for thestate S1 and provides the adjusted frequency level to the power supply160. Moreover, in this example, during the state S1, the AFT 138 adjuststhe frequency level Fsl based on a frequency level corresponding to aparametric value generated by the DSP 153 for the state S1 and providesthe adjusted frequency level to the power supply 162. As anotherexample, during the state S2, the AFT 132 adjusts the frequency levelFp2 based on a frequency level associated with a parametric valuegenerated by the DSP 140 for the state S2 and provides the adjustedfrequency level to the power supply 160. Moreover, in this example,during the state S2, the AFT 141 adjusts the frequency level Fs2 basedon a frequency level associated with a parametric value that isgenerated by the DSP 153 for the state S2 and provides the adjustedfrequency level to the power supply 162. As yet another example, duringthe state S3, the AFT 134 adjusts the frequency level Fp3 based on afrequency level associated with a parametric value generated by the DSP140 for the state S3 and provides the adjusted frequency level to thepower supply 160. Moreover, in this example, during the state S3, theAFT 142 adjusts the frequency level Fs3 based on a frequency levelassociated with a parametric value that is generated by the DSP 153 forthe state S3 and provides the adjusted frequency level to the powersupply 162.

Furthermore, during a state, a power controller of an RF generatordetermines a power level based on a parametric value received from a DSPof the RF generator. For example, during the state S1, the powercontroller 144 determines a power level based on a parametric valuereceived from the DSP 140 and the power controller 150 determines apower level based on a parametric value received from the DSP 153. Asanother example, during the state S2, the power controller 146determines a power level based on a parametric value received from theDSP 140 and the power controller 152 determines a power level based on aparametric value received from the DSP 153. As yet another example,during the state S3, the power controller 148 determines a power levelbased on a parametric value received from the DSP 140 and the powercontroller 154 determines a power level based on a parametric valuereceived from the DSP 153.

Moreover, during a state, a power controller of an RF generator adjustsa power level of a power supply of the RF generator based on a powerlevel that is generated based on a parametric value and provides theadjusted power level to the power supply. For example, during the stateS1, the power controller 144 adjusts the power level of Ppl based on apower level that is generated from a parametric value for the state S1and provides the adjusted power level to the power supply 160. In thisexample, during the state S1, the power controller 150 adjusts the powerlevel of Psi based on a power level that is generated from a parametricvalue for the state S1 and provides the adjusted power level to thepower supply 162. As another example, during the state S2, the powercontroller 146 adjusts the power level of Pp2 based on a power levelthat is generated from a parametric value for the state S2 and providesthe adjusted power level to the power supply 160. In this example,during the state S2, the power controller 152 adjusts the power level ofPs2 based on a power level that is generated from a parametric value forthe state S2 and provides the adjusted power level to the power supply162. As yet another example, during the state S3, the power controller148 adjusts the power level of Pp3 based on a power level that isgenerated from a parametric value for the state S3 and provides theadjusted power level to the power supply 160. In this example, duringthe state S3, the power controller 154 adjusts the power level of Ps3based on a power level that is generated from a parametric value for thestate S3 and provides the adjusted power level to the power supply 162.

During a state, a power supply of an RF generator generates a power RFsignal having an adjusted frequency level for the state received from anAFT of the RF generator and having an adjusted power level for the statereceived from a power controller of the RF generator, and supplies thepower signal via a corresponding RF cable, the impedance matchingcircuit 106, and the RF transmission line 184 to the plasma chamber 104.For example, during the state S1, the power supply 160 generates a powersignal having the adjusted frequency level received from the AFT 130 andhaving the adjusted power level received from the power controller 144,and supplies the power signal via the RF cable 180, the impedancematching circuit 106, and the RF transmission line 184 to the plasmachamber 104. Similarly, in this example, during the state S1, the powersupply 162 generates a power signal having the adjusted frequency levelreceived from the AFT 138 and having the adjusted power level receivedfrom the power controller 150, and supplies the power signal via the RFcable 182, the impedance matching circuit 106, and the RF transmissionline 184 to the plasma chamber 104.

As another example, during the state S2, the power supply 160 generatesa power signal having the adjusted frequency level received from the AFT132 and having the adjusted power level received from the powercontroller 146, and supplies the power signal via the RF cable 180, theimpedance matching circuit 106, and the RF transmission line 184 to theplasma chamber 104. Similarly, in this example, during the state S2, thepower supply 162 generates a power signal having the adjusted frequencylevel received from the AFT 141 and having the adjusted power levelreceived from the power controller 152, and supplies the power signalvia the RF cable 182, the impedance matching circuit 106, and the RFtransmission line 184 to the plasma chamber 104.

As yet another example, during the state S3, the power supply 160generates a power signal having the adjusted frequency level receivedfrom the AFT 134 and having the adjusted power level received from thepower controller 148, and supplies the power signal via the RF cable180, the impedance matching circuit 106, and the RF transmission line184 to the plasma chamber 104. Similarly, in this example, during thestate S3, the power supply 162 generates a power signal having theadjusted frequency level received from the AFT 142 and having theadjusted power level received from the power controller 154, andsupplies the power signal via the RF cable 182, the impedance matchingcircuit 106, and the RF transmission line 184 to the plasma chamber 104.

In an embodiment, a single controller is used instead of the powercontroller 144 and the AFT 130, a single controller is used instead ofthe power controller 146 and the AFT 132, and a single controller isused instead of the power controller 148 and the AFT 134. In someembodiments, a single controller is used instead of the power controller150 and the AFT 138, a single controller is used instead of the powercontroller 152 and the AFT 141, and a single controller is used insteadof the power controller 154 and the AFT 142.

In some embodiments, the z MHz RF generator is used in addition to the xand y MHz RF generators in the system 100. The z MHz RF generator may bea 60 MHz RF generator when the x MHz RF generator is a 2 MHz RFgenerator and the y MHz RF generator is a 27 MHz RF generator. The z MHzRF generator has similar structure as that of the x or y MHz RFgenerator and has similar connections as those of the x or y MHz RFgenerator with components of the system 100 outside the x or y MHz RFgenerator. For example, the z MHz RF generator includes three powercontrollers, three AFTs, a DSP, an ADC, a sensor, and a power supply. Asanother example, the DSP of the z MHz RF generator is coupled with theTool UI 151 to receive the pulsed signal 102. As another example, thepower supply of the z MHz RF generator is coupled to the lower electrode120 of the plasma chamber 104 via an RF cable (not shown), the impedancematching circuit 106, and the RF transmission line 184.

It should be noted that the embodiments described herein are describedusing three states. In some embodiments, more than three states may beused.

FIG. 2 is an embodiment of a graph 190 that illustrates the states S1,S2, and S3. The graph 190 plots power versus time t. Each state S1, S2,or S3 is associated with a logic level. For example, the state S1 has ahigh logic level, the state S2 has a medium logic level, and the stateS3 has a low logic level. The high logic level ‘c’ has a higher powerlevel than the medium logic level b′, which has a higher power levelthan the low logic level ‘a’. As an example, the state S1 has the low,medium, or high logic level. As an example, the state S2 has the low,medium, or high logic level. As an example, the state S3 has the low,medium, or high logic level. In some embodiments, the states S1, S2, andS3 represent a step function.

Each state S1, S2, or S3 lasts for an equal time period. For example, atime period T1 of occurrence of the state S1 is the same as a timeperiod T2 of occurrence of the state S2 or a time period T3 ofoccurrence of the state S3. In some embodiments, a state lasts for anunequal time compared to one or more of remaining states. For example,the state S1 lasts for a different time period than the state S2, whichlasts for a different time period than the state S3. In this example,the time period of the state S3 may be the same as or different from thetime period of the state S1. As another example, the state S1 lasts fora longer time period than the state S2, which lasts for a shorter timeperiod than the state S3.

FIG. 3 is a diagram of an embodiment of a graph 201 that illustratesdifferent time periods for different states. The graph 201 plots powerversus time. The states S1 and S2 occur for the same time periods andthe state S3 occurs for a different time period than the time period forthe state S2 or S3. For example, the state S1 occurs for a time periodt1, the state S2 occurs for a time period t2, and the state S3 occursfor a time period t3. The time period t3 is longer than the time periodt1 or t2.

In some embodiments, any two of the states S1, S2, and S3 occur for thesame time period and the remaining state occurs for a different timeperiod. For example, the state S1 occurs for the same time period asthat of occurrence of the state S3 and the time period of occurrence isdifferent from that of the state S2. As another example, the state S2occurs for the same time period as that of occurrence of the state S3and the time period of occurrence is different from that of the stateS1.

FIG. 4 is a diagram of an embodiment of a system 210 for selecting,during production, one of AFTs 220, 222, or 224 based on a state of thepulsed signal 102. The system 210 includes a select logic 226, the AFTs220, 222, and 224, a digital clock source 228, the plasma chamber 104,the impedance matching circuit 106, and a power supply 232.

The select logic 226, the AFTs 220, 222, and 224, and the power supply232 are implemented within the x MHz RF generator or the y MHz RFgenerator. When the AFTs 220, 222, and 224 are implemented within the xMHz RF generator, the AFT 220 is an example of the AFT 130, the AFT 222is an example of the AFT 132, the AFT 224 is an example of the AFT 134,and the power supply 232 is an example of the power supply 160 (FIG. 1).Similarly, when the AFTs 220, 222, and 224 are implemented within the yMHz RF generator, the AFT 220 is an example of the AFT 138, the AFT 222is an example of the AFT 141, the AFT 224 is an example of the AFT 142,and the power supply 232 is an example of the power supply 162 (FIG. 1).

Examples of the select logic 226 include a multiplexer. When the selectlogic 226 includes the multiplexer, the pulsed signal 102 is received atselect inputs of the multiplexer.

In various embodiments, the select logic 226 includes a processor. In anembodiment, the select logic 226 is implemented within the DSP 140 orthe DSP 153.

The digital clock source 228 is used to operate the power supply 232synchronous with a digital clock signal generated by the digital clocksource 228. In some embodiments, the digital clock signal is synchronouswith the pulsed signal 102. For example, the digital clock signal hasthe same phase as that of the pulsed signal 102. As another example, aphase of the digital clock signal is within a pre-determined phase rangeof a phase of the pulsed signal 102. To illustrate the application ofthe pre-determined phase range, a leading edge of the digital clocksignal of the clock source 228 is a fraction of second behind or beforea leading edge of the pulsed signal 102.

In one embodiment, instead of the digital clock signal from the clocksource 228, the pulsed signal 102 is provided to the power supply 232.

When the pulsed signal 102 is in the state S1, the select logic 226selects the AFT 220. Similarly, when the pulsed signal 102 is in thestate S2, the select logic 226 selects the AFT 222 and when the pulsedsignal 102 is in the state S3, the select logic 226 selects the AFT 224.When the AFT 220 is selected, the AFT 220 provides the frequency levelFp1 to the power supply 232. Similarly, when the AFT 222 is selected,the AFT 222 provides the frequency level Fp2 to the power supply 232 andwhen the AFT 224 is selected, the AFT 224 provides the frequency levelFp3 to the power supply 232.

In embodiments in which the AFTs 220, 222, and 224 are located withinthe y MHz RF generator, when the AFT 220 is selected, the AFT 220provides the frequency level Fs1 to the power supply 232. Similarly, inthese embodiments, when the AFT 222 is selected, the AFT 222 providesthe frequency level Fs2 to the power supply 232 and when the AFT 224 iselected, the AFT 224 provides the frequency level Fs3 to the powersupply 232

In some embodiments, the select logic 226 selects between powercontrollers instead of the AFTs 220, 222, and 224. For example, theselect logic 226 is coupled to the power controllers 144, 146, and 148of the x MHz RF generator (FIG. 1). In this example, the select logic226 selects the power controller 144 when the pulsed signal 102 is inthe state S1, selects the power controller 146 when the pulsed signal102 is in the state S2, and selects the power controller 148 when thepulsed signal 102 is in the state S3. As another example, the selectlogic 226 is coupled to the power controllers 150, 152, and 154 of the yMHz RF generator (FIG. 1). In this example, the select logic 226 selectsthe power controller 150 when the pulsed signal 102 is in the state S1,selects the power controller 152 when the pulsed signal 102 is in thestate S2, and selects the power controller 154 when the pulsed signal102 is in the state S3.

In various embodiments, when the power controller 144 of the x MHz RFgenerator is selected during the state S1, the power controller 144provides the power level Ppl to the power supply 232 and when the powercontroller 146 of the x MHz RF generator is selected during the stateS2, the power controller 146 provides the power level Pp2 to the powersupply 232. Moreover, when the power controller 148 of the x MHz RFgenerator is selected during the state S3, the power controller 148provides the power level Pp3 to the power supply 232.

Similarly, in some embodiments, when the power controller 150 of the yMHz RF generator is selected during the state S1, the power controller150 provides the power level Psi to the power supply 232 and when thepower controller 152 of the y MHz RF generator is selected during thestate S2, the power controller 152 provides the power level Ps2 to thepower supply 232. Moreover, when the power controller 154 of the y MHzRF generator is selected during the state S3, the power controller 154provides the power level Ps3 to the power supply 232.

In a number of embodiments, the select logic 226 is implemented withinthe z MHz RF generator and functions in a similar manner as thatdescribed herein. For example, the select logic 226 selects between AFTsof the z MHz RF generator or between power controllers of the z MHz RFgenerator based on a state of the pulsed signal 102.

FIG. 5 is a diagram of an embodiment of a system 200 for controlling,during production, a frequency and/or power of an RF signal that isgenerated by the y MHz RF generator based on a state of the pulsedsignal 102 and a change in impedance of the plasma within the plasmachamber 104. The DSP 153 of the y MHz RF generator receives the pulsedsignal 102 from the Tool UI 151.

When the pulsed signal 102 transitions from the state S3 to the state S1and when the x MHz RF generator supplies forward power having the powerlevel Pp1 and having the frequency level Fp1 to the plasma chamber 104,impedance of plasma within the plasma chamber 104 changes. When theimpedance of plasma within the plasma chamber 104 changes as a result oftransition of the pulsed signal 102 from the state S3 to the state S1,the sensor 212 measures the complex voltage and complex current beingtransferred via the RF cable 182. The sensor 212 provides themeasurement of the complex voltage and complex current to the ADCconverter 222, which converts the measurements from an analog format toa digital format. The digital values of the measurement of the complexvoltage and complex current are provided to the DSP 153.

It should further be noted that in one embodiment, the DSP 153 lacksreception of the pulsed signal 102. Rather, in this embodiment, the DSP153 receives another digital pulsed signal that may not be synchronouswith the pulsed signal 102. In one embodiment, the other digital pulsedsignal received by the DSP 153 is synchronous with the pulsed signal102.

During the state S1 of the pulsed signal 102, e g, immediately after thestate transition from the state S3 to the state S1 of the pulsed signal102, etc., the DSP 153 calculates a first parametric value, e.g., asquare root of a ratio of the digital reflected power signal and thedigital forward power signal, a gamma value, a voltage standing waveratio (VSWR), a change in impedance, etc., from the complex voltage andcurrent measured during the state S1.

The DSP 153 determines whether the first parametric value is greaterthan or equal to a first threshold. When the DSP 153 determines that thefirst parametric value is greater than or equal to the first threshold,the DSP 153 indicates the same to the AFT 138 and to the powercontroller 150. The AFT 138 determines the frequency level Fs1corresponding to the first parametric value that is at least equal tothe first threshold and provides the frequency level Fsl to the powersupply 162. Moreover, the power controller 150 determines the powerlevel Psi corresponding to the first parametric value that is at leastequal to the first threshold and provides the power level Ps1 to thepower supply 162. For example, the AFT 138 stores within a memorydevice, a table that maps the first parametric value, whose value is atleast equal to the first threshold, with the frequency level Fsl and thepower controller 150 stores within a memory device a mapping between thepower level Psi and the first parametric value, whose value is at leastequal to the first threshold.

On the other hand, when the DSP 153 determines that the first parametricvalue is less than the first threshold, the DSP 153 indicates the sameto the AFT 142 and to the power controller 154. The AFT 142 determinesthe frequency level Fs3 corresponding to the first parametric valuebeing less the first threshold and provides the frequency level Fs3 tothe power supply 162. Moreover, the power controller 154 determines thepower level Ps3 corresponding to the first parametric value being lessthan the first threshold and provides the power level Ps3 to the powersupply 162. For example, the AFT 142 stores within a memory device, atable that maps the first parametric value, whose value is less than thefirst threshold, with the frequency level Fs3 and the power controller154 stores within a memory device a mapping between the power level Ps3and the first parametric value, whose value is less than the firstthreshold.

Upon receiving a frequency level, e.g., a frequency level Fs1, Fs3,etc., and a power level, e.g., Psi, Ps3, etc., the power supply 162generates an RF signal having the frequency level and the power leveland supplies the RF signal via the RF cable 182, the impedance matchingcircuit 106, and the RF transmission line 184 to the plasma chamber 104.For example, an amplifier of the power supply 162 supplies forward powerhaving a power level that is proportional, e.g., same as, multiple of,etc. to the power level Psi and having the frequency level Fs1 via theRF cable 182, the impedance matching circuit 106, and the RFtransmission line 184 to the plasma chamber 104.

When the pulsed signal 102 transitions from the state S1 to the state S2and when the x MHz RF generator supplies forward power having the powerlevel Pp2 and having the frequency level Fp2 to the plasma chamber 104,impedance of plasma within the plasma chamber 104 changes. When theimpedance of plasma within the plasma chamber 104 changes as a result oftransition of the pulsed signal 102 from the state S1 to the state S2,the sensor 212 measures the complex voltage and complex current beingtransferred via the RF cable 182. The sensor 212 provides themeasurement of the complex voltage and complex current to the ADCconverter 222, which converts the measurements from an analog format toa digital format. The digital values of the measurement of the complexvoltage and complex current are provided to the DSP 153.

Moreover, during the state S2 of the pulsed signal 102, e g, immediatelyafter the state transition from the state S1 to the state S2 of thepulsed signal 102, etc., the DSP 153 calculates a second parametricvalue, e.g., a square root of a ratio of the digital reflected powersignal and the digital forward power signal, a gamma value, a voltagestanding wave ratio (VSWR), a change in impedance, etc., from thecomplex voltage and current measured during the state S2.

The DSP 153 determines whether the second parametric value is greaterthan a second threshold. When the DSP 153 determines that the secondparametric value is greater than or equal to the second threshold, theDSP 153 indicates the same to the AFT 141 and to the power controller152. The AFT 141 determines the frequency level Fs2 corresponding to thesecond parametric value that is at least equal to the second thresholdand provides the frequency level Fs2 to the power supply 162. Moreover,the power controller 152 determines the power level Ps2 corresponding tothe second parametric value that is at least equal to the secondthreshold and provides the power level Ps2 to the power supply 162. Forexample, the AFT 141 stores within a memory device, a table that mapsthe second parametric value, whose value is at least equal to the secondthreshold, with the frequency level Fs2 and the power controller 152stores within a memory device a mapping between the power level Ps2 andthe second parametric value, whose value is at least equal to the secondthreshold.

On the other hand, when the DSP 153 determines that the secondparametric value is less than the second threshold, the DSP 153indicates the same to the AFT 138 and to the power controller 150. TheAFT 138 determines the frequency level Fs1 corresponding to the secondparametric value being less the second threshold and provides thefrequency level Fs1 to the power supply 162. Moreover, the powercontroller 150 determines the power level Ps1 corresponding to thesecond parametric value being less than the second threshold andprovides the power level Psi to the power supply 162. For example, theAFT 138 stores within a memory device, a table that maps the secondparametric value, whose value is less than the second threshold, withthe frequency level Fs1 and the power controller 150 stores within amemory device a mapping between the power level Ps1 and the secondparametric value, whose value is less than the second threshold.

When the pulsed signal 102 transitions from the state S2 to the state S3and when the x MHz RF generator supplies forward power having the powerlevel Pp3 and having the frequency level Fp3 to the plasma chamber 104,impedance of plasma within the plasma chamber 104 changes. When theimpedance of plasma within the plasma chamber 104 changes as a result oftransition of the pulsed signal 102 from the state S2 to the state S3,the sensor 212 measures the complex voltage and complex current beingtransferred via the RF cable 182. The sensor 212 provides themeasurement of the complex voltage and complex current to the ADCconverter 222, which converts the measurements from an analog format toa digital format. The digital values of the measurement of the complexvoltage and complex current are provided to the DSP 153.

Furthermore, during the state S3 of the pulsed signal 102, e.g.,immediately after the state transition from the state S2 to the state S3of the pulsed signal 102, etc., the DSP 153 calculates a thirdparametric value, e.g., a square root of a ratio of the digitalreflected power signal and the digital forward power signal, a gammavalue, a voltage standing wave ratio (VSWR), a change in impedance,etc., from the complex voltage and current measured during the state S3.

The DSP 153 determines whether the third parametric value is greaterthan a third threshold. When the DSP 153 determines that the thirdparametric value is greater than or equal to the third threshold, theDSP 153 indicates the same to the AFT 142 and to the power controller154. The AFT 142 determines the frequency level Fs3 corresponding to thethird parametric value being at least equal to the third threshold andprovides the frequency level Fs3 to the power supply 162. Moreover, thepower controller 154 determines the power level Ps3 corresponding to thethird parametric value being at least equal to the third threshold andprovides the power level Ps3 to the power supply 162. For example, theAFT 142 stores within a memory device, a table that maps the thirdparametric value, whose value is at least equal to the third threshold,with the frequency level Fs3 and the power controller 154 stores withina memory device a mapping between the power level Ps3 and the thirdparametric value, whose value is at least equal to the third threshold.

On the other hand, when the DSP 153 determines that the third parametricvalue is less than the third threshold, the DSP 153 indicates the sameto the AFT 141 and to the power controller 152. The AFT 141 determinesthe frequency level Fs2 corresponding to the third parametric valuebeing less the third threshold and provides the frequency level Fs2 tothe power supply 162. Moreover, the power controller 152 determines thepower level Ps2 corresponding to the third parametric value being lessthan the third threshold and provides the power level Ps2 to the powersupply 162. For example, the AFT 141 stores within a memory device, atable that maps the third parametric value, whose value is less than thethird threshold, with the frequency level Fs2 and the power controller152 stores within a memory device a mapping between the power level Ps2and the third parametric value, whose value is less than the thirdthreshold.

The use of a parametric value to change RF power provided by the powersupply 162 results in plasma stability. Also, the plasma stability isbased on real-time measurement of complex voltage and current. Thisreal-time measurement provides accuracy in stabilizing the plasma.

In the embodiments in which the z MHz RF generator is used in additionto using the x and y MHz RF generators, the z MHz RF generator iscoupled to the Tool UI 151, and the pulsed signal 102 is sent from theTool UI 151 to the z MHz RF generator. The z MHz RF generator functionsin a manner similar to the y MHz RF generator. For example, during astate of the pulsed signal 102, it is determined whether a parametricvalue exceeds a threshold. Based on the determination of the parametricvalue, a first level or a second level of power and a first level or asecond level of frequency is provided to a power supply of the z MHz RFgenerator.

In an embodiment, the first threshold, the second threshold, and thethird threshold are generated during a training routine, e.g., alearning process. During the training routine, when the x MHz RFgenerator changes its RF power signal from a first power level to asecond power level, there is an impedance mismatch between one or moreportions, e.g., plasma, etc., within the plasma chamber 104 and the zMHz RF generator. The x MHz RF generator changes a level of its RF powersignal from the first power level to the second power level when a stateof the pulsed signal 102 changes from S3 to S1. In this case, the y MHzRF generator has its frequency and power tuned when the x MHz RFgenerator starts supplying power at the power level Ppl. To reduce theimpedance mismatch, the y MHz RF generator starts tuning, e.g.,converging, to a power level and to a frequency level. The convergencemay be determined by the DSP 153 based on a standard deviation oranother technique. To allow the y MHZ RF generator more time to convergeto the power level and to the frequency level, the x MHZ RF generator iskept at the second power level for an extended period of time than ausual period of time. The usual period of time is an amount of time inwhich the impedance mismatch is not reduced, e.g., removed.

When the y MHz RF generator converges to the power level and thefrequency level, the converged power level is stored as the power levelPs1 within the power controller 150 and the converged frequency level isstored as the frequency level Fs1 within the AFT 138. The firstthreshold is generated from the power level Ps1 during the trainingroutine and the first threshold corresponds to the frequency level Fs1.For example, the sensor 212 measures complex voltage and complex currentduring the training routine. The sensor 212 measures the complex voltageand complex current during the training routine when the frequency ofthe y MHz RF generator is Fs1. The DSP 153 receives the complex voltageand complex current and generates the first threshold from the complexvoltage and complex current measured during the training routine.

Similarly, during the training routine, the second and third thresholdsare determined by the DSP 153.

FIG. 6 is a diagram of an embodiment of a table 250 illustrating acomparison of a change in impedance with a threshold to determine apower level or a frequency level of an RF signal supplied by an RFgenerator. When the state of the pulsed signal changes from the state S1to the state S2, it is determined whether a change in impedance Δz12 ofplasma is greater than the second threshold, indicated as ‘m’. Upondetermining that the change in the impedance Δz12 is at least equal tothe second threshold m, the power level Ps2 or the frequency level Fs2are provided to the power supply 162 of the y MHz RF generator. On theother hand, upon determining that the change in the impedance Δz12 isless than the second threshold m, the power level Psi or the frequencylevel Fs1 are provided to the power supply 162 of the y MHz RFgenerator.

Similarly, when the state of the pulsed signal changes from the state S2to the state S3, it is determined whether a change in impedance Δz23 ofplasma is greater than the third threshold, indicated as ‘n’. Upondetermining that the change in the impedance Δz23 is greater than thethird threshold n, the power level Ps3 or the frequency level Fs3 areprovided to the power supply 162 of the y MHz RF generator. On the otherhand, upon determining that the change in the impedance Δz23 is lessthan the third threshold n, the power level Ps2 or the frequency levelFs2 are provided to the power supply 162 of the y MHz RF generator.

Moreover, when the state of the pulsed signal changes from the state S3to the state S1, it is determined whether a change in impedance Δz31 ofplasma is greater than the first threshold, indicated as ‘o’. Upondetermining that the change in the impedance Δz31 is greater than thefirst threshold o, the power level Psi or the frequency level Fs1 areprovided to the power supply 162 of the y MHz RF generator. On the otherhand, upon determining that the change in the impedance Δz31 is lessthan the first threshold o, the power level Ps3 or the frequency levelFs3 are provided to the power supply 162 of the y MHz RF generator.

In some embodiments, instead of a change in impedance, anotherparametric value, e.g., gamma, VSWR, etc., may be used to determine apower level and/or a frequency level to provide to the power supply 162.

FIG. 7 is a diagram of an embodiment of a system 260 for selecting,during production, AFT 220, 222, or 224 based on a state of the pulsedsignal 102 and based on whether a parametric value exceeds a threshold.When the pulsed signal 102 is in the state S1 and a parametric valuemeasured during the state S1 is at least equal to the first threshold,the select logic 226 selects the AFT 220. On the other hand, when thepulsed signal 102 is in the state S1 and a parametric value measuredduring the state S1 is less than the first threshold, the select logic226 selects the AFT 224.

When the select logic 226 includes the multiplexer, a signal indicatingthat a parametric value during a state of the pulsed signal 102 is atleast equal to or less than the threshold is received at select inputsof the multiplexer from a DSP 270.

The DSP 270 is an example of the DSP 153 (FIG. 1). Based on a complexcurrent and a complex voltage received from a sensor 272 during thestate S1, the DSP 270 determines the first parametric value. The DSP 270further determines that the first parametric value is at least equal tothe first threshold and provides a signal indicating the determinationto the select logic 226. The select logic 226 selects the AFT 220 uponreceiving the signal indicating the determination that the firstparametric value is at least equal to the first threshold. On the otherhand, the DSP 270 determines that the first parametric value determinedduring the state S1 of the pulsed signal 102 is less than the firstthreshold and provides a signal indicating the determination to theselect logic 226. The select logic 226 selects the AFT 224 uponreceiving the signal indicating the determination that the firstparametric value is less than the first threshold. The sensor 272 is anexample of the sensor 212 (FIG. 1) of the y MHz RF generator.

Moreover, based on a complex current and a complex voltage received froma sensor 272 during the state S2, the DSP 270 determines the secondparametric value. The DSP 270 further determines that the secondparametric value is at least equal to the second threshold and providesa signal indicating the determination to the select logic 226. Theselect logic 226 selects the AFT 222 upon receiving the signalindicating the determination that the second parametric value is atleast equal to the second threshold. On the other hand, the DSP 270determines that the second parametric value determined during the stateS2 of the pulsed signal 102 is less than the second threshold andprovides a signal indicating the determination to the select logic 226.The select logic 226 selects the AFT 220 upon receiving the signalindicating the determination that the second parametric value is lessthan the second threshold.

Furthermore, based on a complex current and a complex voltage receivedfrom a sensor 272 during the state S3, the DSP 270 determines the thirdparametric value. The DSP 270 further determines that the thirdparametric value is at least equal to the third threshold and provides asignal indicating the determination to the select logic 226. The selectlogic 226 selects the AFT 224 upon receiving the signal indicating thedetermination that the third parametric value is at least equal to thethird threshold. On the other hand, the DSP 270 determines that thethird parametric value determined during the state S3 of the pulsedsignal 102 is less than the third threshold and provides a signalindicating the determination to the select logic 226. The select logic226 selects the AFT 222 upon receiving the signal indicating thedetermination that the third parametric value is less than the thirdthreshold.

In some embodiments, the select logic 226 selects between powercontrollers instead of the AFTs 220, 222, and 224. For example, theselect logic 226 is coupled to the power controllers 150, 152, and 154of the y MHz RF generator (FIG. 1). In this example, the select logic226 selects the power controller 150 upon receiving the signalindicating the determination that the first parametric value is at leastequal to the first threshold and selects the power controller 154 uponreceiving the signal indicating the determination that the firstparametric value is less than the first threshold. As another example,the select logic 226 selects the power controller 152 upon receiving thesignal indicating the determination that the second parametric value isat least equal to the second threshold and selects the power controller150 upon receiving the signal indicating the determination that thesecond parametric value is less than the second threshold. As yetanother example, the select logic 226 selects the power controller 154upon receiving the signal indicating the determination that the thirdparametric value is at least equal to the third threshold and selectsthe power controller 152 upon receiving the signal indicating thedetermination that the third parametric value is less than the thirdthreshold.

In a number of embodiments, the select logic 226 is implemented withinthe z MHz RF generator and functions in a similar manner as thatdescribed herein. For example, the select logic 226 selects between AFTsof the z MHz RF generator or between power controllers of the z MHz RFgenerator based on a state of the pulsed signal 102 and based on whethera parametric value exceeds a threshold.

FIG. 8A is a diagram of embodiments of graphs 302, 304, 306, and 308.

Each graph 302, 304, 306, and 308 plots power values in kilowatts (kW)as a function of time t. As indicated in graph 302, a 2 MHz powersignal, which is a power signal supplied by the 2 MHz power supply has apower value of a4 during the states S1 and S2 and has a power value of 0during the state S3. Also, a 60 MHz power signal, which is a powersignal supplied by the 60 MHz power supply has a power value of a1during the state S1, has a power value of a2 during the state S2, andhas a power value of a3 during the state S3. The power value of a4 isgreater than the power value of a3, which is greater than the powervalue of a2. The power value of a2 is greater than the power value ofa1, which is greater than zero.

As indicated in the graph 304, the 60 MHz power signal has a power valuea0 during state S3. The power value of a0 is less than the power valueof a1. Moreover, as indicated in graph 306, the 60 MHz signal has thepower value of a2 during the state S1, the power value of a1 during thestate S2, and the power value of a3 during the state S3. As indicated ingraph 308, the 60 MHz signal has the power value of a2 during the stateS1, the power value of a1 during the state S2, and the power value of a0during the state S3.

FIG. 8B is a diagram of embodiments of graphs 310, 312, 314, and 316.Each graph 310, 312, 314, and 316 plots power values in kW as a functionof time t. As indicated in graph 310, a 60 MHz power signal has thepower value of a1 during the state S1, has a power value of a2 duringthe state S2, and has the power value of a2 during the state S3.

As indicated in the graph 312, a 60 MHz power signal has the power valueof a1 during the state S1, has the power value of a2 during the stateS2, and has a power value of a1 during the state S3. Moreover, asindicated in graph 314, a 60 MHz signal has a power value of a2 duringthe state S1, the power value of a1 during the state S2, and the powervalue of a1 during the state S3. As indicated in graph 316, a 60 MHzsignal has the power value of a2 during the state S1, the power value ofa1 during the state S2, and the power value of a2 during the state S3.

FIG. 9A is a diagram of embodiments of graphs 320, 322, 324, and 326.Each graph 320, 322, 324, and 326 plots power values in kW as a functionof time t. As indicated in graph 320, a 60 MHz power signal has thepower value of a1 during the state S1, has the power value of a2 duringthe state S2, and has the power value of a3 during the state S3.Moreover, in graph 320, a 2 MHz power signal has the power value of a4during the state S1, has the power value of a4 during the state S2, andhas the power value of a0 during the state S3. The power value of a0 isless than the power value of a1 and is greater than zero.

Moreover, as indicated in graph 322, a 60 MHz power signal has the powervalue of a2 during the state S1, has the power value of a3 during thestate S2, and has the power value of a1 during the state S3. Also, asindicated in graph 324, a 60 MHz power signal has the power value of a2during the state S1, has the power value of a1 during the state S2, andhas the power value of a3 during the state S3. Furthermore, as indicatedin graph 326, a 60 MHz power signal has the power value of a3 during thestate S1, has the power value of a2 during the state S2, and has thepower value of a1 during the state S3.

FIG. 9B is a diagram of embodiments of graphs 328, 330, 332, and 334.Each graph 328, 330, 332, and 334 plots power values in kW as a functionof time t. As indicated in graph 328, a 60 MHz power signal has thepower value of a2 during the state S1, has the power value of a3 duringthe state S2, and has the power value of a3 during the state S3.Moreover, in graph 330, a 60 MHz power signal has the power value of a2during the state S1, has the power value of a3 during the state S2, andhas the power value of a2 during the state S3. Furthermore, in graph332, a 60 MHz power signal has the power value of a2 during the stateS1, has the power value of a1 during the state S2, and has the powervalue of a1 during the state S3. Also, in graph 334, a 60 MHz powersignal has the power value of a2 during the state S1, has the powervalue of a1 during the state S2, and has the power value of a2 duringthe state S3.

FIG. 10A is a diagram of embodiments of graphs 336, 338, 340, and 342.Each graph 336, 338, 340, and 342 plots power values in kW as a functionof time t. As indicated in graph 336, a 27 MHz power signal, which is apower signal supplied by the 27 MHz power supply has a power value ofa31 during the states S1, S2, and S3. The power value of a31 is greaterthan the power value of a3 and less than the power value of a4. Theremaining of graph 336 is similar to the graph 302 (FIG. 8A).

As indicated in each of graph 338, 340, and 342, a 27 MHz power signalhas a power value of a31 during the states S1, S2, and S3. Moreover, theremaining of graph 338 is similar to the graph 304 (FIG. 8A), theremaining of graph 340 is similar to the graph 306 (FIG. 8A), and theremaining of graph 342 is similar to the graph 308 (FIG. 8A).

In some embodiments, the power value a31 is between zero and the powervalue of a4.

FIG. 10B is a diagram of embodiments of graphs 344, 346, 348, and 350.Each graph 344, 346, 348, and 350 plots power values in kW as a functionof time t. As indicated in graph 344, a 27 MHz power signal, which is apower signal supplied by the 27 MHz power supply has a power value ofa31 during the states S1, S2, and S3. The remaining of graph 344 issimilar to the graph 310 (FIG. 8B).

As indicated in each of graph 346, 348, and 350, a 27 MHz power signalhas a power value of a31 during the states S1, S2, and S3. Moreover, theremaining of graph 346 is similar to the graph 312 (FIG. 8B), theremaining of graph 348 is similar to the graph 314 (FIG. 8B), and theremaining of graph 350 is similar to the graph 316 (FIG. 8B).

FIG. 11A is a diagram of embodiments of graphs 352, 354, 356, and 358.Each graph 352, 354, 356, and 358 plots power values in kW as a functionof time t. As indicated in graph 352, a 27 MHz power signal, which is apower signal supplied by the 27 MHz power supply has a power value ofa31 during the states S1, S2, and S3. The remaining of graph 352 issimilar to the graph 320 (FIG. 9A).

As indicated in each of graph 354, 356, and 358, a 27 MHz power signalhas a power value of a31 during the states S1, S2, and S3. Moreover, theremaining of graph 354 is similar to the graph 322 (FIG. 9A), theremaining of graph 356 is similar to the graph 324 (FIG. 9A), and theremaining of graph 358 is similar to the graph 326 (FIG. 9A).

FIG. 11B is a diagram of embodiments of graphs 360, 362, 364, and 366.Each graph 360, 362, 364, and 366 plots power values in kW as a functionof time t. As indicated in each graph 360, 362, 364, and 366, a 27 MHzpower signal has a power value of a31 during the states S1, S2, and S3.The remaining of graph 360 is similar to the graph 328 (FIG. 9B).Moreover, the remaining of graph 362 is similar to the graph 330 (FIG.9B), the remaining of graph 364 is similar to the graph 332 (FIG. 9B),and the remaining of graph 366 is similar to the graph 334 (FIG. 9B).

FIG. 12A is a diagram of embodiments of graphs 368, 370, 372, and 374.Each graph 368, 370, 372, and 374 plots power values in kW as a functionof time t. As indicated in each graph 368, 370, 372, and 374, a 27 MHzpower signal has a power value of a31 during the states S1 and S2, andhas a power value of a32 during the state S3. The remaining of graph 368is similar to the graph 302 (FIG. 8A). Moreover, the remaining of graph370 is similar to the graph 304 (FIG. 8A), the remaining of graph 372 issimilar to the graph 306 (FIG. 8A), and the remaining of graph 374 issimilar to the graph 308 (FIG. 8A).

FIG. 12B is a diagram of embodiments of graphs 376, 378, 380, and 382.Each graph 376, 378, 380, and 382 plots power values in kW as a functionof time t. As indicated in each graph 376, 378, 380, and 382, a 27 MHzpower signal has a power value of a31 during the states S1 and S2, andhas a power value of a32 during the state S3. The power value of a32 isgreater than the power value a31. The remaining of graph 376 is similarto the graph 310 (FIG. 8B). Moreover, the remaining of graph 378 issimilar to the graph 312 (FIG. 8B), the remaining of graph 380 issimilar to the graph 314 (FIG. 8B), and the remaining of graph 382 issimilar to the graph 316 (FIG. 8B).

FIG. 13A is a diagram of embodiments of graphs 384, 386, 388, and 390.Each graph 384, 386, 388, and 390 plots power values in kW as a functionof time t. As indicated in graph 384, a 27 MHz power signal has a powervalue of a31 during the states S1 and S2, and has a power value of a32during the state S3. The remaining of graph 384 is similar to the graph320 (FIG. 9A). Moreover, the remaining of graph 386 is similar to thegraph 322 (FIG. 9A), the remaining of graph 388 is similar to the graph324 (FIG. 9A), and the remaining of graph 390 is similar to the graph326 (FIG. 9A).

FIG. 13B is a diagram of embodiments of graphs 392, 394, 396, and 398.Each graph 392, 394, 396, and 398 plots power values in kW as a functionof time t. As indicated in each graph 392, 394, 396, and 398, a 27 MHzpower signal has a power value of a31 during the states S1 and S2, andhas a power value of a32 during the state S3. The remaining of graph 392is similar to the graph 328 (FIG. 9B). Moreover, the remaining of graph394 is similar to the graph 330 (FIG. 9B), the remaining of graph 396 issimilar to the graph 332 (FIG. 9B), and the remaining of graph 398 issimilar to the graph 334 (FIG. 9B).

FIG. 14A is a diagram of embodiments of graphs 402, 404, 406, and 408.Each graph 402, 404, 406, and 408 plots power values in kW as a functionof time t. As indicated in each graph 402, 404, 406, and 408, a 27 MHzpower signal has a power value of a32 during the states S1 and S2, andhas a power value of a31 during the state S3. The remaining of graph 402is similar to the graph 302 (FIG. 8A). Moreover, the remaining of graph404 is similar to the graph 304 (FIG. 8A), the remaining of graph 406 issimilar to the graph 306 (FIG. 8A), and the remaining of graph 408 issimilar to the graph 308 (FIG. 8A).

FIG. 14B is a diagram of embodiments of graphs 410, 412, 414, and 416.Each graph 410, 412, 414, and 416 plots power values in kW as a functionof time t. As indicated in each graph 410, 412, 414, and 416, a 27 MHzpower signal has a power value of a32 during the states S1 and S2, andhas a power value of a31 during the state S3. The remaining of graph 410is similar to the graph 310 (FIG. 8B). Moreover, the remaining of graph412 is similar to the graph 312 (FIG. 8B), the remaining of 414 issimilar to the graph 314 (FIG. 8B), and the remaining of graph 416 issimilar to the graph 316 (FIG. 8B).

FIG. 15A is a diagram of embodiments of graphs 418, 420, 422, and 424.Each graph 418, 420, 422, and 424 plots power values in kW as a functionof time t. As indicated in graph 418, a 27 MHz power signal has a powervalue of a32 during the states S1 and S2, and has a power value of a31during the state S3. The remaining of graph 418 is similar to the graph320 (FIG. 9A). Moreover, the remaining of graph 420 is similar to thegraph 322 (FIG. 9A), the remaining of graph 422 is similar to the graph324 (FIG. 9A), and the remaining of graph 424 is similar to the graph326 (FIG. 9A).

FIG. 15B is a diagram of embodiments of graphs 426, 428, 430, and 432.Each graph 426, 428, 430, and 432 plots power values in kW as a functionof time t. As indicated in each graph 426, 428, 430, and 432, a 27 MHzpower signal has a power value of a32 during the states S1 and S2, andhas a power value of a31 during the state S3. The remaining of graph 426is similar to the graph 328 (FIG. 9B). Moreover, the remaining of graph428 is similar to the graph 330 (FIG. 9B), the remaining of graph 430 issimilar to the graph 332 (FIG. 9B), and the remaining of graph 432 issimilar to the graph 334 (FIG. 9B).

It is noted that although the above-described embodiments are describedwith reference to parallel plate plasma chamber, in one embodiment, theabove-described embodiments apply to other types of plasma chambers,e.g., a plasma chamber including an inductively coupled plasma (ICP)reactor, a plasma chamber including an electron-cyclotron resonance(ECR) reactor, etc. For example, the power supplies 160 and 162 arecoupled to an inductor within the ICP plasma chamber.

It should be noted that although the above-described embodiments relateto providing the 2 MHz RF signal and/or 60 MHz RF signal and/or 27 MHzRF signal to the lower electrode 120 and grounding the upper electrode122, in several embodiments, the 2 MHz, 60 MHz, and 27 MHz signals areprovided to the upper electrode 122 while the lower electrode 120 isgrounded.

In one embodiment, the operations performed by an AFT and/or a powercontroller of an RF generator are performed by a DSP of the RFgenerator. For example, the operations, described herein, as performedby the AFT 130, 132, and 134 are performed by the DSP 140 (FIG. 1). Asanother example, the operations, described herein, as performed by theAFT 138, the AFT 141, the AFT 142, the power controller 150, the powercontroller 152, and the power controller 154 are performed by the DSP153 (FIG. 1).

Embodiments described herein may be practiced with various computersystem configurations including hand-held devices, microprocessorsystems, microprocessor-based or programmable consumer electronics,minicomputers, mainframe computers and the like. The embodiments canalso be practiced in distributed computing environments where tasks areperformed by remote processing devices that are linked through anetwork.

With the above embodiments in mind, it should be understood that theembodiments can employ various computer-implemented operations involvingdata stored in computer systems. These operations are those requiringphysical manipulation of physical quantities. Any of the operationsdescribed herein that form part of the embodiments are useful machineoperations. The embodiments also relates to a device or an apparatus forperforming these operations. The apparatus may be specially constructedfor a special purpose computer. When defined as a special purposecomputer, the computer can also perform other processing, programexecution or routines that are not part of the special purpose, whilestill being capable of operating for the special purpose. Alternatively,the operations may be processed by a general purpose computerselectively activated or configured by one or more computer programsstored in the computer memory, cache, or obtained over a network. Whendata is obtained over a network the data may be processed by othercomputers on the network, e.g., a cloud of computing resources.

One or more embodiments can also be fabricated as computer-readable codeon a non-transitory computer-readable medium. The computer-readablemedium is any data storage device, e.g., a memory device, etc., that canstore data, which can be thereafter be read by a computer system.Examples of the computer-readable medium include hard drives, networkattached storage (NAS), ROM, RAM, compact disc-ROMs (CD-ROMs),CD-recordables (CD-Rs), CD-rewritables (CD-RWs), magnetic tapes andother optical and non-optical data storage devices. Thecomputer-readable medium can include computer-readable tangible mediumdistributed over a network-coupled computer system so that thecomputer-readable code is stored and executed in a distributed fashion.

Although the method operations were described in a specific order, itshould be understood that other housekeeping operations may be performedin between operations, or operations may be adjusted so that they occurat slightly different times, or may be distributed in a system whichallows the occurrence of the processing operations at various intervalsassociated with the processing, as long as the processing of the overlayoperations are performed in the desired way.

One or more features from any embodiment may be combined with one ormore features of any other embodiment without departing from the scopedescribed in various embodiments described in the present disclosure.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications can be practiced within the scope ofthe appended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein, but may be modifiedwithin the scope and equivalents of the appended claims.

1. A method for pulsing radio frequency (RF) generators, comprising:generating a pulsed signal; controlling a primary RF generator togenerate a primary RF signal having a first primary quantitative level;controlling the first primary quantitative level of the primary RFsignal to transition to a second primary quantitative level based on thepulsed signal; controlling the second primary quantitative level of theprimary RF signal to transition to a third primary quantitative levelbased on the pulsed signal; controlling a secondary RF generator togenerate a secondary RF signal having a first secondary quantitativelevel; and controlling the first secondary quantitative level of thesecondary RF signal to transition to a second secondary quantitativelevel.
 2. The method of claim 1, wherein said controlling the firstsecondary quantitative level of the secondary RF signal to transition tothe second secondary quantitative level is performed based on the pulsedsignal.
 3. The method of claim 1, further comprising controlling thesecond secondary quantitative level of the secondary RF signal totransition to a third secondary quantitative level based on the pulsedsignal.
 4. The method of claim 3, wherein the first secondaryquantitative level, the second secondary quantitative level, and thethird secondary quantitative level are determined during a trainingroutine that is performed before the method is executed to process asubstrate.
 5. The method of claim 1, wherein the first secondaryquantitative level is the same as the second secondary quantitativelevel.
 6. The method of claim 1, wherein the first secondaryquantitative level is different from the second secondary quantitativelevel.
 7. The method of claim 1 further comprising determining that athreshold is exceeded when the first primary quantitative level of theprimary RF signal transitions to the second primary quantitative level,wherein said controlling the first secondary quantitative level of thesecondary RF signal to transition to the second secondary quantitativelevel is performed upon said determining that the threshold is exceeded.8. The method of claim 1, further comprising sending the pulsed signalto the primary and secondary RF generators.
 9. The method of claim 1,wherein the digital pulsed signal has three states.
 10. A controller forpulsing radio frequency (RF) generators, comprising: a processorconfigured to generate a pulsed signal, wherein the processor isconfigured to control a primary RF generator to generate a primary RFsignal having a first primary quantitative level, wherein the processoris configured to control the primary RF generator to transition thefirst primary quantitative level of the primary RF signal to transitionto a second primary quantitative level, wherein the transition from thefirst primary quantitative level to the second primary quantitativelevel occurs based on the pulsed signal, wherein the processor isconfigured to control the primary RF generator to transition the secondprimary quantitative level of the primary RF signal to a third primaryquantitative level, wherein the transition from the second primaryquantitative level to the third primary quantitative level occurs basedon the pulsed signal, wherein the processor is configured to control asecondary RF generator to generate a secondary RF signal having a firstsecondary quantitative level, and wherein the processor is configured tocontrol the secondary RF generator to transition the first secondaryquantitative level of the secondary RF signal to a second secondaryquantitative level; and a memory device coupled to the processor. 11.The controller of claim 10, wherein the processor is configured tocontrol the first secondary quantitative level of the secondary RFsignal to transition to the second secondary quantitative level based onthe pulsed signal.
 12. The controller of claim 10, wherein the processoris configured to control the secondary RF generator to transition thesecond secondary quantitative level of the secondary RF signal to athird secondary quantitative level, wherein the transition from thesecond secondary quantitative level to the third secondary quantitativelevel occurs based on the pulsed signal.
 13. The controller of claim 12,wherein the processor is configured to control the primary RF generatorto achieve the first primary quantitative level, the second primaryquantitative level, and the third primary quantitative level duringprocessing of a substrate, wherein the processor is configured tocontrol the secondary RF generator to achieve the first secondaryquantitative level and the second secondary quantitative level duringprocessing of the substrate, wherein the first secondary quantitativelevel, the second secondary quantitative level, and the third secondaryquantitative level are determined during a training routine that isexecuted before the primary and second RF generators are controlled toprocess the substrate.
 14. The controller of claim 10, wherein the firstsecondary quantitative level is the same as the second secondaryquantitative level.
 15. The controller of claim 10, wherein the firstsecondary quantitative level is different from the second secondaryquantitative level.
 16. The controller of claim 10, wherein thesecondary RF generator is configured to determine that a threshold isexceeded when the first primary quantitative level of the primary RFsignal transitions to the second primary quantitative level, wherein thesecondary RF generator is configured to transition from the firstsecondary quantitative level of the secondary RF signal to the secondsecondary quantitative level in response to the determination that thethreshold is exceeded.
 18. The controller of claim 10, wherein theprocessor is configured to send the pulsed signal to the primary andsecondary RF generators.
 19. A controller system for pulsing radiofrequency (RF) generators, comprising: a processor configured togenerate a pulsed signal, a first controller coupled to the processor,wherein the first controller is configured to control a primary RF powersupply to generate a primary RF signal having a first primaryquantitative level, wherein the first controller is configured tocontrol the primary RF power supply to transition the first primaryquantitative level of the primary RF signal to transition to a secondprimary quantitative level, wherein the transition from the firstprimary quantitative level to the second primary quantitative leveloccurs based on the pulsed signal, wherein the first controller isconfigured to control the primary RF power supply to transition thesecond primary quantitative level of the primary RF signal to a thirdprimary quantitative level, wherein the transition from the secondprimary quantitative level to the third primary quantitative leveloccurs based on the pulsed signal; and a second controller coupled tothe processor, wherein the second controller is configured to control asecondary RF power supply to generate a secondary RF signal having afirst secondary quantitative level, and wherein the second controller isconfigured to control the secondary RF power supply to transition thefirst secondary quantitative level of the secondary RF signal to asecond secondary quantitative level.
 20. The controller system of claim19, wherein the second controller is configured to control the firstsecondary quantitative level of the secondary RF signal to transition tothe second secondary quantitative level based on the pulsed signal.